双层钢桁架斜交梁桥力学特性研究

Study on Mechanical Characteristics of Double-deck Steel Truss Skew-beam Bridge

摘要:

为了分析双层钢桁架斜交梁桥的受力特点，建立了斜交角为0°、10°、20°、30°、40°、50°和60°的钢桁架梁整体有限元分析模型。对比研究了双层钢桁架梁的静力特性、静力稳定性和动力特性。研究结果表明：斜交角增大时，钢桁架梁上弦杆、下弦杆和腹杆受力普遍增大；斜交角由0°增加至60°时，杆件轴力增加不超过20%，面内弯矩增加50%~203%；斜交角小于20°时，腹杆、上弦杆和下弦杆恒、活载轴力变化基本普遍小于5%，面内弯矩普遍小于10%；斜交角增大时，双层钢桁架梁整体稳定性降低小于4%；斜交角增大时，结构自振频率和整体刚度减小；斜交角小于50°时，结构自振频率减小不超过2.4%。

Abstract:

In order to analyze the mechanical characters of double-deck steel truss skew-beam bridge, the overall finite element analysis models of steel truss beams with skew angles of 0°, 10°, 20°, 30°, 40°, 50° and 60° are established. The static characteristics, static stability and dynamic characteristic of double-deck steel truss beam are compared and studied. The research results show that when the skew angle increases, the forces on the upper chord bar, lower chord bar and web bar of the steel truss beam generally increase. When the skew angle increase from 0°to 60°, the increase in the axial force of the bars shall not exceed 20%, but the in-plane bending moment increases by 50% to 203%. When the skew angle is less than 20⁰, the changes in the constant and live axial forces of the web bar, upper chord bar and lower chord bar are basically generally less than 5%, and the in-plane bending moment is generally less than 10%. When the skew angle increases, the overall stability of the double-deck steel truss beam decreases by less than 4%. When the skew angle increases, the natural frequency of the structure and the overall stiffness decrease. And when the skew angle is less than 50°, the natural frequency of the structure decreases by no more than 2.4%.